[Clinical application of a classification based on crucial curvature of coronal imbalance in degenerative lumbar scoliosis].

To present efficacy of clinical application of a classification based on crucial curvature of coronal imbalance in degenerative lumbar scoliosis (DLS). A case series study. Clinical data of 61 cases (8 males, 53 females) who underwent posterior correction surgery for DLS from January 2019 to January 2021 were retrospectively analyzed. The mean age was (71.7±6.2) years (ranged 60-82 years). According to the direction of C plumb line (CPL) deviated from central sacral vertical line (CSVL) and orientation of L coronal tilt, the author determined which one was the crucial curve. If CPL deviated from CSVL in the same direction as concave side of the thoracolumbar curve and L coronally tilts opposite direction of CPL deviates from CSVL, then the crucial curve was thoracolumbar curve (type 1). On the contrary, if CPL deviated from CSVL in the same direction as concave side of the lumbosacral curve and L coronally tilts consist with direction of CPL deviates from CSVL, then the crucial curve was lumbosacral curve (type 2). According to absolute value of coronal balance distance (|CBD|), each type of patients was divided into two groups, respectively, namely coronal balance (CB) (|CBD|≤3 cm) and coronal imbalance (CIB) (|CBD|>3 cm). Changes of Cobb angles of thoracolumbar curve and lumbosacral curve and CBD were recorded and analyzed. The rate of preoperative CIB was 55.7% (34/61) in all the patients. Of the patients, 23 cases were classified as type 1 and 38 cases as type 2. The rate of preoperative CIB was 34.8% (8/23) in type 1 patients and 68.4% (26/38) in type 2. The rate of postoperative CIB was 27.9% (17/61) in all the patients, with 13.0% (3/23) in type 1 and 36.8% (14/38) in type 2. The |CBD| of CB group in type 1 patients decreased from (2.6±1.4) cm before the operation to (1.5±1.0) cm after (=0.015); and the correction rate of thoracolumbar curve (68.8%±18.4%) was significantly higher than that of lumbosacral curve (34.5%±23.9%) (=0.005). The |CBD| of CB group in type 2 patients decreased from (2.6±3.0) cm before the operation to (1.6±1.2) cm after (=0.027); the correction rate of lumbosacral curve (71.3%±18.6%) was higher than that of thoracolumbar curve (57.3%±21.1%), but the difference was not statistically significant (=0.546). There was no significant difference in |CBD| of CIB group in type 2 patients before and after the operation (=0.222); the correction rate of lumbosacral curve (38.3%±14.8%) was significantly lower than that of thoracolumbar curve (53.6%±16.0%) (=0.001). There was a correlation between the change of CBD (3.8±1.5) cm and the difference in correction rate between thoracolumbar and lumbosacral curve (32.3%±19.6%) in CB group in type 1 patients after surgery (=0.904, <0.001). There was a correlation between the change of CBD (1.9±2.2) cm and the difference in correction rate between lumbosacral and thoracolumbar curve (14.0%±26.2%) in CB group in type 2 patients after surgery (=0.960, <0.001). Clinical application of a classification based on crucial curvature of coronal imbalance in DLS is satisfactory, and its combination with matching correction can effectively prevent the occurrence of coronal imbalance after spinal correction surgery.